Pleco Help Please??!!!?!?!?!?

id keep it till you get the 40. i have a 55 with a fluval 405 filter. i have a common pleco thats 8 inches a 6 inch vampire pleco, several neon tetras andaround a dozen red cherry shrimp so i dont think that one common pleco in a 40 gallon would cause any problems with anykind of fish if you have a good canister filter i also have a under gravel filter with powerhead cause i tend to over feed